1. Field of the Invention
The present invention relates to a hybrid vehicle such as a hybrid automobile, the hybrid vehicle having a propeller shaft to transmit a driving force in the front-rear direction of the vehicle body. In particular, the present invention relates to a mounting structure of a battery unit for a hybrid vehicle.
2. Description of the Related Art
Some vehicles such as an automobile have a propeller shaft. Those vehicles include, for example, automobiles that use an FR (Front engine Rear drive) or AWD (All-Wheel Drive) drive system. The propeller shaft is disposed under the floor of a vehicle body to transmit a driving force in the front-rear direction of the vehicle body, the driving force being generated by an engine or the like.
A vehicle having such a propeller shaft may be converted to an electric vehicle or a hybrid vehicle. An electric vehicle and a hybrid vehicle need to be provided with a battery unit with a large capacity. Mounting a battery unit reduces the cargo space in the rear of the backseat and makes it difficult to maintain proper weight balance in the vehicle longitudinal direction. In Japanese Unexamined Patent Application Publication No. 2000-247261, part of the dead space is effectively used for the battery unit, whereby a battery unit does not have to be mounted in the cabin space. In this case, specifically, the propeller shaft and the battery unit are disposed under the floor of the vehicle body. The battery unit needs to be replaced for every predetermined period. Therefore, the battery unit is preferably disposed below the propeller shaft so as to be able to be replaced without any contact with the propeller shaft.
However, when the battery unit is disposed below the propeller shaft, the impact absorption performance of the vehicle upon a collision, for example, may be adversely affected. When the battery unit is disposed below the propeller shaft, the engine of the vehicle may be pushed back upon a collision and the propeller shaft may be bent. Accordingly, the bent propeller shaft comes into contact with the battery unit. The magnitude of the bend angle of the propeller shaft is limited by the presence of the battery unit. This imposes a limit on the magnitude of backward push to the engine, and thus the impact absorption performance in relation to the backward push is reduced.
Thus, a vehicle having a propeller shaft preferably has a member capable of controlling bending of the propeller shaft, so that the adverse effect to the impact absorption performance is reduced. It is desirable that the battery unit disposed under the floor should be provided with a function of such control.